[clang] __sys builtin support (PR #145079)

[Daniel Paoliello via cfe-commits]

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@@ -5471,19 +5471,21 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
   }
 
   if (BuiltinID == clang::AArch64::BI_ReadStatusReg ||
-      BuiltinID == clang::AArch64::BI_WriteStatusReg) {
+      BuiltinID == clang::AArch64::BI_WriteStatusReg ||
+      BuiltinID == clang::AArch64::BI__sys) {
     LLVMContext &Context = CGM.getLLVMContext();
 
     unsigned SysReg =
       E->getArg(0)->EvaluateKnownConstInt(getContext()).getZExtValue();
 
     std::string SysRegStr;
-    llvm::raw_string_ostream(SysRegStr) <<
-                       ((1 << 1) | ((SysReg >> 14) & 1))  << ":" <<
-                       ((SysReg >> 11) & 7)               << ":" <<
-                       ((SysReg >> 7)  & 15)              << ":" <<
-                       ((SysReg >> 3)  & 15)              << ":" <<
-                       ( SysReg        & 7);
+    unsigned SysRegOp0 = (BuiltinID != clang::AArch64::BI__sys)
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dpaoliello wrote:

Can you switch the branches here? I'd prefer to avoid a not-equals comparison in a ternary operator.

https://github.com/llvm/llvm-project/pull/145079